1. The Field of the Invention
The present invention relates generally to orthopedic medicine, and more precisely, to systems and methods for restricting relative motion between vertebrae.
2. The Relevant Technology
Many people experience back pain. Back pain is not only uncomfortable, but can be particularly debilitating. Many people who wish to participate in sports, manual labor, or even sedentary employment are unable to do so because of pains that arise from motion of or pressure on the spinal column. Such pains are often caused by traumatic, inflammatory, metabolic, synovial, neoplastic and degenerative disorders of the spine.
The intervertebral discs that separate adjacent vertebrae from each other serve to provide stiffness that helps to restrain relative motion of the vertebrae in flexion, extension, axial rotation, and lateral bending. However, a damaged disc may provide inadequate stiffness along one or more modes of spinal motion. Inadequate stiffness may result in excessive relative vertebral motion when the spine is under a given load, as when the patient uses the muscles of the back. Such excessive relative motion may cause further damage to the disc, thereby causing back pain and ultimately, requiring replacement of the disc and/or other operations to decompress nerves affected by central, lateral or foraminal stenosis.
Some stabilization devices have been proposed to restrict, but not entirely prevent, relative motion between adjacent vertebrae. Such devices are often somewhat complex and/or bulky. Many such devices cannot be tailored to limit the types of motion (i.e., flexion/extension, axial rotation, or lateral bending) that are most painful. Additionally, in the event that stabilization ultimately becomes insufficient, most known stabilization devices do not provide any mechanism that can be used to more fully secure the spinal motion segment.